Résumé
At the threshold for conscious perception, the very same stimulus may or may not access consciousness, depending on the observer’s cognitive state [1]. In such a context, subliminal information can be temporarily maintained in non-conscious working memory (WM), as evidenced by the ability to guess above chance level unseen stimuli features [2]. However, little is known about the influence of biological rhythms on the variability of conscious access and non-conscious WM. Building on recent findings highlighting the respiratory modulation of human cognition [3], we measured the breathing phase (inhalation vs exhalation) of thirty participants during a near-threshold Gabor orientation discrimination task [4]. Importantly, when the Gabor was not consciously perceived, observers were required to make a guess on its orientation. In addition, participants had to report as fast as possible by a button press pseudo-randomized occurrences (10% of trials) of a brief supraliminal white point. Reaction time on this parallel task was used as a measure of attention levels. Given the large interindividual variability in non-conscious WM, we used an unsupervised machine learning approach, together with classical signal detection theory, to dissociate the bad from the good guessers. For bad guessers (n=17), exhalation impaired conscious processing, as evidenced by lower perceptual awareness and longer reaction times in the parallel attentional task. In contrast, for good guessers (n=13), exhalation improved non-conscious WM. Taken together, these results suggest that the human brain prioritizes the conscious processing of external events during inhalation, while information perceived duringexhalation is preferentially processed non-consciously.